Conventional mobile devices are often dedicated to performing a specific application. For example, a mobile phone provides telephony services, a personal digital assistant (PDA) provides a way to organize addresses, contacts and notes, a media player plays content, email devices provide email communication, etc. Modern mobile devices can include two or more of these applications. Due to the size limitation of a typical mobile device, such mobile devices may need to rely on a network or other remote service to support these multiple applications. For example, a map service may provide maps to a mobile device over a network, which can be used with one or more applications running on the mobile device. The introduction of a positioning system integrated with, or coupled to, the mobile device provides additional opportunities for providing location-based services.
Modern positioning systems include satellite based positioning systems, such as Global Positioning System (GPS), cellular network positioning based on “cell IDs” and WiFi positioning technology based on a WiFi networks. The satellite based positioning systems tend to be the most accurate. These satellite systems, however, often consume more power than the other positioning systems, and rely on the visibility of multiple satellites to determine a position estimate.